<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>渲染帧</title>

    <style>
      * {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
      }
      .ball {
        width: 100px;
        height: 100px;
        background-color: #008c8c;
        border-radius: 50%;
        position: fixed;
        top: 0;
        left: 50%;
        transform: translateX(-50%);
      }
    </style>
  </head>
  <body>
    <div class="ball"></div>

    <script>
      var domBall = document.querySelector('.ball');
      console.log(domBall);
    </script>
  </body>
</html>
